It is known that hazardous and non-hazardous fluid transportation and storage tanks of all types are susceptible to damage and ruptures, e.g., punctures through the tank wall, and leaking from a variety of mechanisms, e.g., valves and seals. An example of a known technology taught in U.S. Pat. No. 635,939 mitigates fluid loss by employing canvas patches using electromagnets to hold the patches in place over a hole or rupture in a petroleum transportation marine vessel thus reducing fluid loss. U.S. Pat. No. 5,009,179 shows an oil-impervious flexible sheet held in place along top and side edges by electromagnets while the bottom edge is left open. In U.S. Pat. No. 5,036,786, a patch is disclosed which includes a steel mesh blanket and a steel sheet, where the patch includes electromagnetic bars therein. U.S. Pat. No. 5,165,356 discloses a patch including a rigid plate member, a cushion layer, and a pliable sealing layer, held in place against a ruptured wall by electromagnets. Each of the foregoing references discloses a variation of a patch held in an operative position by electromagnets and thereby attached in some manner at the periphery of the patch.
U.S. Pat. Nos. 5,038,701 and 5,195,446 each disclose a flexible material for covering an opening in the hull of a ship. The covering material includes four layers of material with an array of electromagnets embedded between two of the layers. U.S. Pat. No. 5,009,180 discloses a patch system free of electromagnets that utilizes a series of ropes or cables, sealing hoses, inflatable bladders, and the like, to set a sheet in place covering a rupture in the hull of a ship.
The foregoing technologies are set up and applied manually, typically some time after a tank has been injured. Each mechanism comprises a patch or flexible blanket applied over an existing hole or rupture in the wall of a tank or petroleum transportation marine vessel. It should be appreciated that numerous attempts have been made to mitigate fluid loss from damaged and leaking containers; especially attempts at controlling the spillage of bulk liquid cargos such as oil from petroleum tanker ships. A known method is an attempt to control such leakage through the ship's design and construction of a second hull where an inner hull would protect the cargo from being lost should damage be inflicted upon the outer hull of the ship. However, this method is extremely expensive prohibiting most from obtaining tankers of such design. Another negative consideration of the double hull tanker design involves a substantial decrease in a ship's stability.
There also exists in the art other methods and devices that are not an integral part of the tanker ship or storage container's structural design that attempt to mitigate fluid loss from a damaged area. Such devices are either pre-deployed as in the case of an inner liner or liquid barrier, which offers limited protection by deflecting and yielding to the energy of impact, or employed sometime after an accident or catastrophic event occurs, as in the case of expandable bladder and pump operated liquid transfer systems. A further design provides for a protective layer placed against the hull of a tank with a flexible liner placed on top of the protective layer. The transported liquid, e.g., oil, is filled into the compartment containing the protective layer and containment liner arrangement. However, this arrangement only offers limited protection as it anticipates only a finite number of accident scenarios and must withstand the forces of impact as well as abrasion, cuts, tears and punctures associated with a violent tanker collision and possible catastrophic tank failure.
Yet another design employs a flexible bladder and pump system wherein the pump system transfers the fluid cargo from the damaged tank to a containment bladder in the event of a tank rupture. However, this method is prone to significant fluid loss because of the inherent lag time during which the transfer of large volumes of fluid from the original tank to the flexible bladder container. Moreover, several devices relate to double walled tanks for railway tank cars and underground storage tanks which provide for an outer tank and an inner containment tank with energy absorbing areas in between. These designs are static, preventative devices integral to a tanks structure and do not anticipate leaks due to failure of valves, seals or fittings. Further, the double walled tank construction is static and cannot respond to an active leak rendering such preventive measures useless once a leak occurs for any reason.
U.S. Pat. No. 3,906,880 discloses an oil leak pollution control device for containing oil within the hull of an oil tanker that has been damaged. Operatively, this device requires that it is placed manually by crew members creating a disadvantage by not being automatically deployed at the time of an accident. Additionally, the foregoing device employs the use of a pump to recover oil from a damaged compartment by transferring it to a vinyl container during which time substantial amounts of fluid would be lost through the damaged area of the tank shell.
U.S. Pat. No. 5,349,914 discloses a device for impeding the spillage of liquid from a damaged hull of a water travelling vessel. However, this device is a static buffering bladder/liner/container system and suffers the distinct disadvantage of having to survive an impact or other catastrophic tank failure to be useful. Additionally, this device is deficient in that it lacks the ability to respond to an active leak should one occur.
U.S. Pat. No. 6,152,059 discloses a device and method for recovering oil by pumping the oil into a prepositioned expandable bladder with the bladder serving to retard the flow of oil out from a damaged oil tanker as well as attempting to retard the flow of seawater into the tank. This method of sealing relies on sufficient pressure being exerted as the weight of the oil presses the bladder up against the wall of the damaged tank. The clear disadvantage of this system is the lag time of the pumping process during which time oil is being lost to the sea. Additionally, the sealing quality of the bladder pressing against the tank wall is directly proportional to the amount of oil contained within the bladder which is variable and therefore incapable of providing a consistent positive seal.
U.S. Pat. Nos. 6,494,156, 6,508,189, 6,609,474, 6,672,235 and 7,322,306 disclose a family of non-permeable bladder containers within a meso-skeletal structure and various methods for connecting, suspending and protecting such bladder containers. Once again however, the static bladder/liner containment technology fails to meet the objectives of an automatic emergency response to a damaged and actively leaking container.
It is apparent that each of the foregoing systems and methods suffers from a variety of drawbacks. None of the aforementioned technologies describes a system which is a preinstalled, existing as a permanent safety system capable of being deployed instantaneously upon demand as an immediate response to an accident. Additionally, no prior technology mentioned above addresses pressure applications such as those encountered in pressurized tanks, e.g., tank trucks or railway tank cars, transporting hazardous gaseous materials under pressure. Furthermore, none of the technologies discussed above are described as being fully automatic in their operation or are otherwise proactively initiated by impact or pressure differential or other electronic sensors. Finally, all of the preceding technologies address only the localized area surrounding a specific rupture site whereas none of the aforementioned technologies provides for complete coverage of the entire tank wall surface area simultaneously.